High-frequency heating arrangement



' Oct; 2 1949- A. J. PINKNEY 2, 5

HIGH-FREQUENCY HEATING ARRANGEMENT Filed Dec. 17, 1947 Q 2 Sheets-Sheet1 .A.J. PINKNEY F IG. 2 INVENTOR 2 Sheets-Sheet 2 Filed Dec. 17, 1947 FIG.3

FIG.4

A.J. PINKNEY INVENTOR Patented Oct. 25, 1949 HIGH-FREQUENCY HEATINGARRANGEMENT Arthur Jack Pinkney, London,v England, assignor to TheHartford National Bank and Trust Company, Hartford, Conn., as trusteeApplication December 17, 1947, Serial No. 792,218 In Great BritainOctober 18, 1944 Section 1, Public Law 690, August 8, 1946 Patentexpires October 18, 1964 6 Claims.

This invention relates to high frequency heat ing arrangementsincorporating a concentrator of the kind consisting of a hollow cylinderof copper or similar highly conducting material provided at one end witha block of like material which is attached to the cylinder and has anaperture for the passage of the work; the block and the cylinder areslotted so that a closed circuit does not exist about the aperture. Thehigh frequency current is supplied to a coil surrounding the cylinder.

With such concentrators it is desirable that the end block shouldsurround the work as closely as possible, and the present invention hasfor its object to enable this desideratum to be achieved quickly andsimply.

According to the present invention the end block is provided with anaperture greater than or at least not smaller than the maximum desiredaperture, the walls of the aperture being so shaped as to form a seatingfor an adaptor ring which is inserted in. the aperture in the end blockand is itself provided with an aperture appropriate to the work. Theadaptor ring is slotted in the same way as the end block and cylinderand consists of similar material. To avoid the production of a closedcircuit about the aperture, the slots in the adaptor ring and theremainder of the concentrator may be aligned, but preferably the adaptoris insulated from the remainder by the interposing of a layer of micafor example.

In practice, a number of interchangeable adaptor rings forming a seriescan be provided for use with a single concentrator. When changing towork of diiferent diameter, it is only necessary to substitute anadaptor ring having an aperture of the appropriate size. If theconcentrator cylinder is arranged. with its axis ver tical and with theblock at its upper end, the adaptor rings can simply rest on the seatingprovided and no securing means'are required.

Certain embodiments of the invention will now be described by way ofexample with reference to the accompanying drawings in which:

Figure 1 is a central vertical section through a high frequency heatingarrangement according to the invention, the section being takensubstantially along the line I--I of Figure 2.

Figure 2 is a top plan view of Figure 1.

Figures 3 to 6 show central sections through alternative forms ofconcentrator rings for use in the arrangement according to Figures 1 and2, Figures 3 to 6 being on a somewhat larger scale than Figures 1 and 2.

Figure 7 illustrates a further embodiment according to the invention.

Referring first to Figures 1 and 2, the main inductor I consists of anumber of turns of square section copper tubing, the consecutive turnsbeing supported at the desired spacing by a number of insulating spacingmembers 2. The two ends 3 of the main inductor coil l are provided withconnections for water or other cooling fluid and are also electricallyconnected to the high frequency source (not shown). Arranged within theinductor coil l is a concentrator unit consisting of a cylindrical body4 and an annular top member 5 constituting the end block, the innerdiameter of the annular member being smaller than the inner diameter ofthe cylindrical body l. As best seen from Figure 2, the concentrator isprovided with a radial slot 5 extending through the annular top member 5and along the length of the cylindrical body 4. The cylindrical body 4is hollow and is provided with water inlet and outlet connections I and8 respectively. The arrangement so far described is supported on aninsulating base plate 9 provided with legs Ill, the concentrator bodybeing secured to the base plate 9 by a number of bolts l4 (Figure 1).The upper face of the annular concentrator member 5 is covered by acover plate I I of insulating material which also covers the top of themain inductor coil l. The cover plate H is secured by means of bolts l2which are embedded in the concentrator member 5 and which receive nutsengaging the outer surface of the cover plate H. The peripheral surfaceof the main inductor coil is enclosed within a cylindrical surround l3of insulating material which extends between the base plate 9 and thecover plate II.

The annular top member 5 of the concentrator has a central apertureconsiderably in excess of the diameter of the work which it is desiredto heat. To adapt the concentrator to the work an adaptor ring i5 isinserted in the central aperture in the annulus 5 and is provided with acentral aperture 16 corresponding to the size of the work to be heated.This inserted concentrator ring [5 is provided with a radial slot ii. Ifthe inserted ring I5 is insulated from the annulus 5 by an interposedlayer of mica or equivalent insulating material capable of withstandingan elevated temperature the slot I! need not be aligned with the slot 6in the annulus 5, but if there is metallic contact between the insertedring l5 and the annulus 5 the slots l1 and 6 must be in registration. Inthe construction illustrated a layer 21 of mica is interposed betweenthe inserted concentrator ring I and the annulus 5. The inserted ring [5is supported in the desired position by means of an annular member [8 ofinsulating material which is secured to the underface of the annulus 5by means of bolts l9 engaging in tapped holes 20 passing through theannulus 5. The concentrator ring I5 is thus removably supported in theannulus 5 and. can consequently be replaced by a ring exhibiting anaperture of different size or shape to suit the particular work which isto be treated. Typical alternatives to the form of inserted ring shownin Figure 1 are illustrated in Figures 3 to 6. Figures 3 to 6 show across-section through the ring I5 with the work aperture IE, but thecrosssection has been taken on such a line that the radial slot l1(Figures 1 and 2) does not appear.

As an alternative to the arrangements shown for supporting the ring I5within the annulus 5, the supporting ring l8 could be dispensed with,the ring [5 being made of conical form tapering downwardly and the innersurface of the annulus 5 forming a corresponding conical seat. Such aconstruction is shown in Fig. 7. In this case the slot in the insertedring must register with the slot 6 in the annulus 5.

If desired, provision can be made for cooling the inserted ring l5 bymaking it hollow and passing a cooling fluid through it, as shown inFig. 7 wherein a hollow ring i5 is supplied with a cooling fluid throughthe conduits 25 and 26.

Moreover the insulating supporting l8 (Figure 1) may comprise or carry ajig for the accurate location of the work in the aperture 15 in the ring15.

I claim:

1. High frequency heating apparatus comprising a coil member forgenerating a high frequency heating field, a first electricallyconductive tubular member fixedly secured within an end portion of saidcoil and provided with a slot longitudinally extending through a Wallportion thereof, and a second electrically conductive tubular memberpositioned within said first tubular member and provided with a slotextending through a wall portion thereof.

2. High frequency heating apparatus comprising a helical coil member forgenerating high frequency heating field, a first electrically conductivecylindrical member fixedly secured Within said coil, a secondelectrically conductive tubular member fixedly secured within an endportion of said coil in abutting relationship to one end of said firstmember, said first and second member being provided with aligned slotsextending through a Wall portion thereof, and a third electricallyconductive tubular member positioned Within said second tubular memberand provided with a slot extending through a Wall portion thereof.

3. High frequency heating apparatus comprising a helical coil member forgenerating a high frequency heating field, a first electricallyconductive cylindrical member fixedly secured within said coil, a secondelectrically conductive annular member fixedly secured within an endportion of said coil in abutting relationship to one end of said firstmember, said first and second members being provided with aligned radialslots, and a third electrically conductive ring member positioned withinsaid annular member and provided with a radial slot.

4. High frequency heating apparatus comprising a helical coil member forgenerating a high frequency heating field, a first electricallyconductive cylindrical member fixedly secured within said coil, a secondelectrically conductive annular member fixedly secured within an endportion of said coil in abutting relationship to one end of saidcylindrical member, said first and second members being electricallyinterconnected, being provided with aligned radial slots and beingelectrically insulated from said helical coil, a third electricallyconductive ring member positioned within said annular member andprovided with a radial slot, and means to electrically insulate saidring member from said annular member.

5. High frequency heating apparatus comprising a helical coil member forgenerating a high frequency heating field, a first electricallyconductive cylindrical member fixedly secured Within said coil andcomprising spaced concentric wall portions, a second electricallyconductive annular member fixedly secured within an end portion of saidcoil in abutting relationship to one end of said cylindrical member,said first and second members being electrically interconnected, beingprovided with aligned radial slots and being electrically insulated fromsaid helical coil, a third electrically conductive ring memberpositioned within said annular member and provided with a radial slot,and means to supply a cooling fluid to the space between said concentricwall portions.

6. High frequency heating apparatus comprising a helical coil member forgenerating a high frequency heating field, a first electricallyconductive cylindrical member fixedly secured within said coil, a secondelectrically conductive annular member fixedly secured within an endpor- REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Name Date Roberds Sept. 24, 1946 Number

